A procedure has been developed to collect, transfer, and analyse volatile organic pyrolysis products of tobacco leaf compounds. The volatiles were collected in a series of three traps on adsorbents that also served as substrates for transfer and for introduction of the volatiles into a gas chromatograph. Analytical procedures are described for three gas chromatographic columns packed, respectively, with the three different adsorbents used in the traps. With this system, volatile pyrolyzates were collected and analysed without the use of cryogenic traps, vacuum manifolds, or gas-sampling valves. The applicability of the procedures is demonstrated for the pyrolysis volatiles of stearic acid, a tobacco constituent
Pyrolytic products of commercial tobacco sheet, flue-cured tobacco leaf, and stems were compared. The yields of acids, bases, neutrals, and phenolics were determined. The neutrals were further characterized by chromatography in order to examine pyrolysis fractions corresponding to biologically active cigarette smoke fractions. Individual phenols, carboxylic acids, polynuclear aromatic hydrocarbons (PAH), and nicotine were determined for sheet and leaf pyrolyzate. Analyses of constituents of various pyrolyzate fractions indicated significantly lower amounts of phenols, PAH, and nicotine in sheet and stem pyrolyzates than in leaf pyrolyzates
Recent studies on the pyrogenesis of tobacco smoke constituents have been reviewed. Where appropriate, representative studies on pyrolyses of compounds reportedly present in tobacco leaf have been included. Various experimental conditions such as temperature, gaseous environment, and thermal stability of precursor were considered in light of current understanding of the smoking process. Attempts to alter the chemical constituents of smoke by use of additives have been discussed. Finally, various smoke constituents have been correlated with pyrolyses of leaf constituents in further hopes of better understanding the complex processes that produce tobacco smoke
The nitrogen analogues of polynuclear aromatic hydrocarbons (aza-arenes) were isolated and identified in a basic fraction of cigarette smoke condensate. Silicic acid chromatography removed the predominant nicotine alkaloids, while gel chromatography on Bio-Beads S-X12 in benzene effectively separated the aza-arenes from interfering aliphatic compounds. In addition, the gel columns separated the aza-arenes by ring number and degree of alkylation on the basis of an adsorption-type mechanism. These gel characteristics facilitated the identifications of a large number of isomeric aza-arenes. Compounds identified included 2-vinylpyridine, 3-vinylpyridine and 2-phenylpyridine as well as quinoline, isoquinoline, 4-azafluorene, benzoquinolines, benzoisoquinolines, 1-azafluoranthene, 7-azafluoranthene, 4-aza-pyrene, 7- azaindole, pyrroloquinoline and their mono-, di- and trimethyl derivatives. All eight possible isomers of benzoquinoline and benzoisoquinoline were found, four of which are being reported for the first time. Evidence was also found for the probable presence of 5,6-benzo-7-azaindole.
Paraffins of tobacco Ieaf were separated by column chromatography on silicic acid. Leaf paraffins were fractionated from other wax constituents by chromatography in a definite sample to substrate to solvent ratio. The developed method was used to evaluate the transfer of paraffins and neophytadiene from leaf to smoke in a reference cigarette. Gas chromatographic separations were performed on a high-temperature liquid phase. Gas chromatography in conjunction with mass spectrometry was used to determine the paraffin composition of a representative flue-cured tobacco, a reference cigarette tobacco, and smoke condensate. It was concluded that paraffins were probably transferred to smoke relatively unchanged, while neophytadiene underwent some pyrolytic decomposition.
R. F. Severson, O. T. Chortyk and W, J. Chamberlain
Smoke from gamma irradiated 1R1 Reference cigarettes was compared to smoke from the non-irradiated cigarettes. Total particulate matter, nicotine, and tar levels decreased with increasing radiation dose. Nicotine was determined by gas chromatography, using 7-methyl- quinoline as an internal standard. Yields of solvent partition fractions of the smoke condensate and of chromatographic fractions of the condensate neutrals did not indicate significant changes in smoke composition resulting from gamma irradiation of the precursor cigarette tobacco. The composition of refined polycyclic aromatic hydrocarbon (PAH) fractions of smoke from irradiated cigarettes appeared to be identical to that of standard cigarettes. The expected decrease in PAH did not occur. It was concluded that gamma irradiation of cigarettes had no major effects on smoke composition.
Methods have been developed for the analyses of the minor high-boiling bases of smoke. Fused silica glass capillary columns coated with Superox-4 were prepared and used successfully for the GC analyses of the basic fraction of smoke, containing compounds covering a wide range of volatility and polarity (nicotine to norbarman). The Superox-4 capillary column also produced an excellent separation of the numerous Nacylalkaloids, which have been reported in tobacco and tobacco smoke. Several new N´-acylalkaloids are reported. The described methodology should be a great asset in future isolation and identification studies of these and other, as yet to be characterized, minor bases of smoke and leaf.
A new chromatographic method utilizing the hydrogen bonding properties of Sephadex LH-20 gel in methanol / chloroform, was developed for the isolation of phenolic acids. This method was applied to the characterization of phenolic acids in flue-cured tobacco. Gel chromatography successfully isolated and concentrated the phenolic acids from other acidic substances and allowed identification and quantitation of these compounds by GC and GC-MS, as their trimethylsilyl derivatives. Compounds identified included: cis- and trans-isomers of p-coumaric, ferulic, caffeic, and sinapic acids; o-, m-, and p-hydroxybenzoic acids; o-hydroxyphenylacetic acid; 2,5- and 3,4-dihydroxybenzoic acids; and 2,3-, 2,5- and 3,4-dihydroxybenzaldehydes. Caffeic acid was the major compound, probably arising from the degradation of the chlorogenic acid of leaf. Aliphatic acids having two or more carboxyl groups were also isolated and included the following: malonic, succinic, fumaric, malic, and citric acids. A dihydroxycinnamaldehyde and a dihydroxynaphthoic acid are reported in tobacco leaf for the first time.
Extensive details are presented for the laboratory preparation of specific glass capillary columns for the gas chromatographic analysis of various phenolic and acidic compounds of leaf and smoke. The chromatography of derivatized and underivatized mono- and dihydroxybenzenes, volatile acids, phenolic acids, and fatty acids is evaluated on both Pyrex glass and fused silica columns prepared by our methodology. The stability, efficiency, and low surface activity of columns prepared from different liquid stationary phases (SE-54, Superox-4, SP-1000, Silar 10C) are illustrated by numerous separations.
O.T.O. T. Chortyk, W. S. Schlotzhauer and R. L. Stedman
The complex polyphenolic pigments of Turkish tobacco have been pyrolyzed to determine their possible contribution to the formation of aromatic compounds, especially polynuclear aromatic hydrocarbons (PAH), of smoke. The dark brown pigments were initially obtained by a basic aqueous extraction of tobacco. Various hydrolytic procedures showed the presence of rutin, chlorogenic acid, and a series of amino acids; some information on the structure of these pigments is presented. The pyrolysis of the pigments was carried out at 850°C and the products were fractionated to reveal the presence of more than a dozen PAH. Addition of pigments to cigarettes gave an increase in the level of benzo[a]pyrene in the smoke. The possible role of the polyphenolic pigments as a source of PAH in smoke is discussed